A Multi-scenario Reputation Estimation Framework and its Resilience Study against Various forms of Attacks

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1 Publishd in th Procdings of th 27 IEEE/IC/CM Intrnational Confrnc on b Intllignc (I'7) Silicon Vally, ov 27, pp Multi-scnario putation Estimation Framwork and its silinc Study against Various forms of ttacks Javd I. Khan Mdia Communications and tworking sarch Laboratory Dpartmnt of Computr Scinc, Knt Stat Univrsity, Knt, H avd@knt.du bstract nlin transactional activitis that involv stablishmnt of trust btwn participating individual sm to rquir a rputation function for th rputation stimation framwork (EF). Thy ar oftn vulnrabl to various kinds of attacks. lso it sms w do not valuat rputation in th sam way in all situations. Using ccam s razor w propos a gnralizd st-thortic rputation function with customizabl componnts that can b changd to mt th rputation rquirmnts in wid varity of rputation assssmnt scnarios. Furthr w idntify svral canonical classs of th functions. Th rsilinc of th framwork is thn analyzd by subcting it to various rputation attacks such as gang attacks, vndtta and Dr Jkyll & Mr. Hyd.. Introduction putation is an ssntial componnt of social mchanics whr to commit various social transactions on party must nd to infr probabl rspons of th othr whil taking a risk. putation is dfind as 'socially constructd labls that xtnd th consquncs of a party's actions across tim, situations, and othr actions' []. nlin rputation is also incrasingly attaining significanc. Li has shown that sllrs with good rputation hav a highr probability of sal and gt highr transaction pric. krlof [2] has shown that a markt brakdown is highly likly if th sllrs cannot convinc th buyrs about th quality of goods and srvics. It sms that rputation in particularly important in th onlin world whr prfct strangrs ar mting in numbrs which has no prcdnc. High rputation can hlp in instilling mor confidnc in th buyr about th sllr. Battalio, Ellul & Jnnings [3] hav shown that rputation plays an important rol in th liquidity provision procss on th floor of th YSE. Ghos t. Said S. Shaikh Brulant Inc 37 Park East Driv Bachwood, H 4422 said.shaikh@brulant.com al [4] suggst that a sllr with bttr rputation can succssfully charg highr prics than compting sllrs of idntical products, and that thir pricing powr incrass with thir rcordd lvl of xprinc. Th Intrnt is also xpanding th varity of intractions in which prfct strangrs ar ngaging. This is manifstd in th mrgnc of social ntworks surrounding numrous digital srvics. n th Intrnt thr is a growing trnd of lik-mindd popl coming togthr to form virtual communitis. Th communitis thus formd indulg in divrs activitis ranging from simpl frindly ntworking to commrc. Th wb is filld with onlin social ntworks, commrc wbsits and P2P systms. lot of data and information is bing shard among individuals. Th building block for this kind of cooprativ bhavior is th mutual trust btwn various individuals. Th trustworthinss of an individual is positivly corrlatd to his/hr rputation. s community siz grows, th individuals ar xposd to scnarios whr thy hav to intract with unknown individuals. In ths scnarios, rputation sms to b a good scal to masur against bfor intracting with strangrs. highr individual rputation most likly corrlats positivly with individual trustworthinss. In spit of ths prcautions, on can b facd with attack scnarios whr sombody is trying to compromis ons rputation. ilson t al ([5]) hav idntifid and cratd taxonomy for rational attacks and thn idntifid th corrsponding solutions if thy xist. Th thrats numratd by Dllarocas ([6]) ar similar to th kind of thrats w hav tackld through our EF. putation sms to b a vry important part of social mchanics. It sms w as a social bing mploy som form of computation to assss rputation of popl in numrous situations. n intrsting qustion is to s what might b th functional and computational form

2 Publishd in th Procdings of th 27 IEEE/IC/CM Intrnational Confrnc on b Intllignc (I'7) Silicon Vally, ov 27, pp of it? Do w all us similar function? Do w us diffrnt functions in diffrnt scnarios? Is thir any rsilinc against various attacks? Currntly, w could find fw vry simpl adhoc functions. In this rsarch w tak a holistic viw to this problm and look closly at various factors which gnrally is attachd in th assssmnt of rputation. thn suggst a gnric rputation function for quantifying th rputation of a pr in any communitylik nvironmnt. ur goal is to hav an attack tolrant gnric systm, which is dynamic and customizabl. In this papr, w prsnt this nw gnric function in sction-2. It can b usd insid a rputation managmnt systm (MS) framwork. Sction-3 prsnts a discussion on various thrats w gnrally ncountr ovr such framwork. Sctions-4 prsnts th rsilinc charactristics of th suggstd function undr svral forms of attacks. 2. putation Modl In this sction, w prsnt a social-transactional modl of a gnralizd rputation stimation systm framwork. This is followd by a discussion of th various factors that influncing th rputation of a pr and towards th nd w prsnt a mathmatical formulation for quantifying rputation. putation is th stimation of an individuals status in a social stup. It is built basd on various social transactions and th valuations of thos transactions. Thus, ths transactions collctivly builds up a mmory about a targt individual and this is stimatd in targt s rputation function. Th valu is usful to stablish trust in a latr transaction involving th targt in various communitis. Social scinc litratur idntifis a numbr of factors that affct rputation, but w considr th ons, that ar th most dominant.(i) pinion about a Transaction (): Gnrally, ach transaction crats an valuation about th goodnss of a pr. putation rlis on ths individual fdbacks or opinions to valuat a stabl masur about th goodnss of a pr. (ii) putation of pinion Providr (): hnvr a pr xprsss an opinion, many social scnarios sm to tak into account as to who xactly is providing this opinion. This factor hlps in wighing crtain opinion mor havily than othrs wigh. (iii) g of th pinion (T): This factor capturs th frshnss of th opinions. Th opinion gts oldr with tim and hnc its impact on th ovrall rputation bcoms lss. (iv) umbr of Transactions (): n avraging function is a bttr mathmatical rprsntation to dtrmin rputation. Hnc, th total numbr of transactions is an important factor in dtrmining rputation irrspctiv of th volum of transaction. (v) Group putation (): Group rputation is takn into considration to somwhat dpict th ral socity whr individuals with high rputation tnd to b associatd with a group whos mmbrs ar also highly rputd. vrthlss, in cass whr thy ar surroundd with low rputation, thy ncourag th lowly rputd mmbrs to improv thir rspctiv rputation. (vi) Impact Paramtrs (X & α): Ths variabls ar usd to control th dirction of influnc and th amount of influnc th abov-mntiond variabls would hav on th ovrall rputation of th pr. Th abov paramtrs can b functionally connctd in many diffrnt forms. us ccam razor principl and suggst th following gnric rputation function (quation ). X X T T α α λ α X T ( ) = m k = k = α X + m = α X +Φ 2. Th Gnric putation Function putation in a socity sms to b positivly corrlatd to opinion, individual rputation of opinion providr and opinion frshnss. Hnc th gnric rputation function is a product of th thr variabls hav usd an avraging function instad of a summation function sinc w wantd to rstrict th valu btwn and. Th dcras in th frshnss of opinion is a gradual procss, hnc w hav usd an xponntial function. Each factor can affct th rputation valuation procss ithr positivly, ngativly or hav no impact (zro impact).th impact variabl X controls th influnc dirction of th various factors. Each factor has its on indpndnt impact variabl. Crtain factors may b mor aggrssivly involvd in th valuation procss as compard to othrs. This bhavior can b capturd by th impact wight variabl α. Each factor has its own controlling α and by assigning th appropriat valus, th impact of crtain variabls can b mad mor pronouncd as oppos to othrs. 2.2 Canonical Classs of th Function Dpnding upon th dploymnt nvironmnt, crtain variabls would impact th rputation whr as othrs wont b part of th dtrmination procss. Thr ar four primary customizabl variabls viz., T, and, thus thr ar sixtn possibl ways to customiz thm. could find at last fiv of ths combinations hav corrsponding ral lif xampls. call thn canonical rputation scnarios. Tabl lists ths canonical scnarios. λ

3 Publishd in th Procdings of th 27 IEEE/IC/CM Intrnational Confrnc on b Intllignc (I'7) Silicon Vally, ov 27, pp am Function Exampl Fading Mmory vraging Function = = α X α X = ( λt) α T X T ( λt) α X +Φ λ adrs xprssing opinions about a book. Mmory lss Summation Function Fading Mmory vraging Function without pinion Crdibility Fading Mmory vraging Function without Community Contxt Factor Mmory lss vraging Function ( t ) α X α X α X = = = = ( = = α α X = t ) = α X = α X = α X ( λt ) α T X T ( λt ) ( λt ) ( λt ) α T X T α X α X α +Φ +Φ α λ λ Tabl : Canonical classification of th rputation function uthors xprssing opinion about thir book Viwrs xprssing opinion about a movi. Critics providing opinion about a movi. 3. Thrats to th Modl In th nxt sctions, w hav prsntd a dtaild dscription of th various attacks that ar possibl on rputation managmnt systms. In sction 3., w introduc th various partis involvd in th attack followd by an xplanation of th various attacks in sction Partis Involvd in an ttack (i) ttackr(s) (T): Th attackr/prptrator can ithr b th prson giving an opinion about th targt individual or th targt individual himslf. assum that th attackr always lis. Th attackr prson/group can b of thr typs. () vrag Group: It contains a mixtur of mmbrs having high rputation and low rputation. (2) Vry Good Group: ll th mmbrs of this group hav high rputation. (3)Vry Bad Group: ll th mmbrs of this group hav low rputation. (ii) Evaluators (EV): Thy rprsnt th gnral population and ar ssntially th Controllr Conglomration, which provids random corrct opinion about th targt individual. assum in our systm that th valuators nvr li and ar always truthful. Th Evaluator contains mmbrs who hav a rang of rputations from high to low. (iii) Targt (TG): Th targt could b a singl individual of a group of individuals. (iv) ffndr (F): Th offndr is th prson who commits somthing bad in th systm for which h should b pnalizd Various putation ttacks Vndtta n attackr may targt a singl usr by giving him a low opinion. This attackr could hav High, Low or vrag Individual putation. Th impact of th attack diffrs dpnding upon th attackr s individual rputation Damaging Gang ttack Th attackr can oin a group of othr attackrs to lssn th rputation of th targt. Th attacking group

4 Publishd in th Procdings of th 27 IEEE/IC/CM Intrnational Confrnc on b Intllignc (I'7) Silicon Vally, ov 27, pp provids unfairly ngativ opinions to th targtd good usr, thrby lowring his rputation Dr Jkyll & Mr. Hyd n offndr starts off in th systm in a wllbhavd mannr. s a rsult, his rputation in th systm gos up. nc his rputation is sufficintly high h turns hostil. 4. Exprimntal Evaluation prformd thr sts of xprimnts to valuat our rputation modl. Through ths xprimnts, w prov that out modl stands it ground in th fac of diffrnt attacks. Th graphs ar plottd with final rputation on Y-axis vrsus th tim of th opinion on th X-axis. 4. Vndtta Th valuator population is random providing honst opinion to th targt. hav a singl targt and a singl attackr. 4.. Class n Function Vndtta sults Th two llipss in figur dnot diffrnt priods of attack. vrall from figur, w can dduc that prsonal attack has a vry limitd or no damaging ffct on th targt rputation if th attackr frquncy is low but can hav a considrabl impact in cas of highr attackr frquncy Class Thr Function Vndtta sult Th rsults for this function show a bhavior similar to th on shown by th fading mmory avraging function Class Four Function Vndtta sults Th rsults for this function show a bhavior similar to th on shown by th fading mmory avraging function. 4.2 Damaging Gang ttack hav a singl targt and a group of attackrs. Th attackrs ar initially part of th valuator group but abruptly turn hostil. Th numbr of mmbrs of th attackr group is st to % of th total numbr of valuator pr Class n Function Damaging Gang sults In figur 4, w can notic small rcovris of th targt s rputation; on of thm is rprsntd by th dottd circl. Through figur 4, w obsrv that though th attackrs manag to bring down th rputation of th targt during th attack priod, thy ar not abl to inflict prmannt damag. Th function rcovrs itslf to th original valu through th honst opinion xprssd by valuators with high rputation and th ag of th opinion variabl Class Thr Function sults obsrv a bhavior similar to th on discussd in sction Th rputation gos down during th attack priod but thn th rcovry starts as soon as th attack is ovr as dpictd in figur Class Four Function sults Th function rsults shown in figur 8 ar similar to th fading mmory avraging function discussd in sction Dr Jkyll & Mr. Hyd Th simulation consists of thr groups. Th valuator group in this scnario consists of th avrag group, th vry good group and th vry bad group. Th simulation dsign is graphically rprsntd in figur Class n Function sults Th Dr Jkyll and Mr. Hyd phnomnon is vividly sn in figur 7. Th valuators punish th targt for his offnc, which rsults in his rputation taking a downward slid. Howvr, h rcovrs his rputation through indulging in honst transaction, again to commit offnc for which h is duly pnalizd. This trnd is sn in figur 7 by th upward and downward movmnt of th rputation function Class Thr Function sults Th rsults obsrvd ar similar to th fading mmory avraging function rsults as shown in fig Class Four Function sults Th rsults obsrvd ar similar to th fading mmory avraging function as shown in figur 9.

5 Publishd in th Procdings of th 27 IEEE/IC/CM Intrnational Confrnc on b Intllignc (I'7) Silicon Vally, ov 27, pp Evaluator ating ttackr pinion ttackr ating Final putation Evaluator pinion Figur : Class on function bhavior whn attackr has random prsonal rputation Evalutor pinion ttackr pinion.3.2. Final puation Figur 2: Class thr function bhavior during Vndtta Prsonal Fight Vry Bad Prsonal Fight Vry Good Prsonal Fight vrag Figur 3: Class four function bhavior during Vndtta.85 ating ttackr pinion ttackr ating Final putation pinion Figur 4: Class on function bhavior whn attackr group mmbrs hav high prsonal rputation

6 Publishd in th Procdings of th 27 IEEE/IC/CM Intrnational Confrnc on b Intllignc (I'7) Silicon Vally, ov 27, pp Evaluator pinion.8.6 ttackr pinion.4.2 Final putation Figur 5: Class thr function bhavior undr Damaging Gang ttack Damaging Gang ttack Good Damaging Gang ttack Bad Damaging Gang ttack vrag Figur 6: Class four function bhavior undr Damaging Gang ttacks pinion Final ating.2 Figur 7: Class on function bhavior valuator group mmbrs hav high prsonal rputations..8.6 Evaluator pinion Final putation Figur 8: Class thr function bhavior during Dr Jkyll & Mr. Hyd attack

7 Publishd in th Procdings of th 27 IEEE/IC/CM Intrnational Confrnc on b Intllignc (I'7) Silicon Vally, ov 27, pp Figur 9: Class four function bhavior for Dr. Jkyll & Mr. Hyd. Jkyll Multipl Vry Good Jkyll Multipl vrag 5. silinc Stratgis aturally, full attack tolranc can not b achivd ust in on layr. It will rquir an intgratd approach involving othr componnts of th onlin systm- particularly involving idntity managmnt, authntication, and non-rpudiation procsss of th ovrall systm. good rputation function should hlp dtction. Through simulations w hav shown th bhavior of th functions undr various attacks or attack signaturs. Th signatur can provid important guidanc towards th dsign of a rsilint framwork. Evry consistnt rapid chang in rputation slop or rputation shift should b a suspct of possibl attack. It is possibl that a rputation shift is gnuin. Howvr, a suspct cas should b subct to furthr analysis. Vndtta attacks can b dtctd and possibly rsistd by looking at th tmporal frquncy and rating uniformity of th origination point of th opinions. Gang attack will rquir a mor gnralizd approach. stricting th rating frquncy for valuations which ar showing strong spatial (distanc in social ntwork) and/or tmporal locality can hlp thwarting distributd yt organizd attacks. Th slop charactristic can provid th rquird limits. Howvr, som problms ar vn hardr. For xampl thr is no dfinit way of distinguishing btwn Damaging Gang and Dr. Jkyll & Mr. Hid kind of attacks. Th numbr of low opinions bing xprssd towards th targt can giv som kind of indication as to which attack is in progrss is Conclusions In this papr w hav discussd a probabl functional form towards stimation of gnralizd rputation. To our knowldg this is on of th first such works. Dfinitly w as a social lmnt mploy som form of computation to assss and updat rputation of popl with whom w dal with. putation sms to b a vry important part of our social mchanics. It sms onlin rputation will b incrasingly high stack asst. In th corporat world thr ar too many xampls whr millions hav bn lost du to loss rputation. Larg stak holdrs will aggrssivly guard thir onlin rputations. lso attmpt will intnsify to compromis it. nvision som form of dtctiv units outlind in sction-5 to b bcom an intgral part of any rputation framwork of th futur for continuous monitoring of suspctd shifts and slctd ratrs. 7. frncs [] C. H. Tinsly, K. M. 'Connor, & B.. Sullivan. Tough guys finish last: Th prils of a distributiv rputation. rganizational Bhavior & Human Dcision Procsss, 88(2), [2].G. krlof, Th Markt for 'Lmons': Quality Uncrtainty and th Markt Mchanism, Th Quartrly Journal of Economics, MIT Prss, vol. 84(3), pags 488-5, ugust.97. [3]. Ellul,. H Jnnings, and. H. Battalio, putation Effcts in Trading on th w York Stock Exchang. F 26 [4] Ghos, nindya, Ipirotis, Panagiotis G. and Sundararaan, run, Th Dimnsions of putation in Elctronic Markts (Fbruary 26). YU Cntr for Digital Economy sarch orking Papr o. CDE-6-2 [5] S. J. ilson, S.. Crosby, D.S. allach. Taxonomy of ational ttack. [6] C. Dllarocas. Immunizing nlin putation porting Systms gainst Unfair atings and Discriminatory Bhavior. CM, Minnapolis, Minnsota, US 2.